Unicorns are mythical creatures, and in medieval lore they were visible only to very select people of exceptional purity. In Silicon Valley, however, if you miss a unicorn, you can always wait for the next one.

After all, there are 90 of them.

In the tech world, of course, a unicorn is not a flitting creature of fancy, but something very different: A startup that is a very tangible, concrete evidence of just how much money is looking for a home in Silicon Valley. "Unicorn" has become a widely used shorthand for startups who have won the techie jackpot: companies that are worth $1 billion or more, solely through fundraising and the generosity and faith of venture capitalists.

Over a dozen unicorns, including Lyft and Pure Storage, a Flash-based enterprise storage company, had a presence at this week's Collision conference in Las Vegas, which bills itself as "a meeting place for people who are both building the companies of tomorrow and managing the companies of today."

The specter over the tributes to startups and techie success is the inevitable fall to earth. Some of those high-flying businesses will never live up to those stratospheric expectations, conceded Paddy Cosgrave, the Irish entrepreneur who runs the conference, as well as the annual Web Summit in Dublin.

"But that has always been the nature of high-growth, high-profile private companies," he added.

In other words: Unicorns don't have wings.

The reality behind the myth

That ultimate flightlessness — the inevitable fall to earth — is partly why in Silicon Valley, “unicorn” has become something of a dirty word.

John Collison, president of the online and mobile payments company Stripe, gives voice to the disdain for unicorns. Collison cofounded Stripe with his brother Patrick, who serves as CEO. The payments company, which lets businesses and individuals process payments and charges a flat 2.9% fee (plus 30 cents) for each transaction, is used by clients such as Apple, Facebook, Twitter, Lyft and Instacart.

Stripe, which does not disclose its financials, qualifies as a unicorn thanks to a $70 million round of funding last winter valuing the company at $3.5 billion.

“I get an involuntary twitch every single time someone refers to us using valuation as kind of a shorthand,” Collison told Mashable.

Tech investors have a rule: For every 100 startups they invest in, 10 of them may become successful. However, just one of those 10 successful startups has the potential to be the next Facebook.

“The focus on valuations seems really misplaced,” maintained Collison, who added the Stripe team doesn’t spend a lot of time thinking or talking about being a member of this growing billion-dollar startup club. Added Collison: “Learning a valuation doesn’t really tell you much about the business and it becomes this weird scoreboard thing or ranked list.”

There's another worry: Such stratospheric numbers have folks wringing their hands, wondering if we're seeing another tech bubble.

The dreaded bubble

This is where the old and young in Silicon Valley diverge.

“It’s real hard to answer, but everybody’s instinct over the age of 22 is, ‘Yeah, we’re in a bubble, because valuations are so high,'” Logitech CEO Bracken Darrell told Mashable.

Bryan Johnson, who cofounded the online payments company Braintree and now runs OS Fund, a $100 million fund aimed squarely at startups working on projects with far-out goals like Planetary Resources for mining asteroids, or Human Longevity, which wants to lengthen the average human lifespan to 120 years.

There is a bubble, Johnson explained — sort of –- but it’s smaller than what we saw in 2000 and only applies to some areas of tech. Consumer companies like Snapchat, for example, don't justify the hype, he suggested, let alone those sky-high valuations.

“I think the bubble is happening because you’re seeing an abundance of capital that is interested in a similar number of investments,” Johnson said. “They understand social media — they understand that kind of business. But for them to jump into, say, hard science is a big jump.”

Some hold out some optimism that the end — or even the middle — of the current boom in valuations doesn't have to be ugly.

"It’s a brutal system," CEO Chet Pipkin told Mashable, but added that the tech industry is seeing its own kind of renaissance. He would know: since Pipkin started the private, Los Angeles-based tech company in 1983, Belkin has evolved into a global business with more than 1,000 employees. Pipkin, meanwhile, is reportedly a billionaire.

Khosla Ventures partner Ben Ling, who has held senior roles at Google and Facebook, suggested the bubble talk is overblown. While the dot-com era of the late 1990s and early 2000s had flops like Pets.com, which lacked sustainable business models, more companies today have the customers, revenue and growth to justify their lofty valuations.

The 11-year-old data software company Palantir may be worth $15 billion, for example, but offers products that help clients sift through big data and make sense of it. In fact, Palantir’s software was reportedly used by the U.S. government to hunt down Osama bin Laden.

Meanwhile, companies like Slack and Snapchat command high valuations ahead of huge profits, Ling explained, because of their "monetization potential." They don't make much now, in other words, but some investors bet they will down the road.

"Pinterest, Snapchat and Slack's valuations are similar to 2007, when many people thought it was crazy that Facebook was valued at $15 billion, but that doesn't look so crazy today," pointed out Ling.

That may be true for industry insiders like Ling, but expect the hand-wringing to continue. Because until these startup unicorns become hugely profitable, their valuations will sound just as far-fetched as ever.

Updated at 8:40 p.m. ET on May 9 to clarify Darrell and Pipkin's quotes.

Mashable
is a global, multi-platform media and entertainment company. Powered by its own proprietary technology, Mashable is the go-to source for tech, digital culture and entertainment content for its dedicated and influential audience around the globe.